Sure they're there.  You just need to zoom in a few times.  The problem here is as follows:

	- all your agents are located at 50x50 and never move, so they're piled up on top of one another

	- you're zoomed way out so the agents are teeny tiny

	- green doesn't help in seeing them here

	- neither does turning off clipping

I suggest initially keeping the display at perhaps 8 times the grid size.

Sean

On Jul 24, 2013, at 9:58 AM, Megan Olsen wrote:

> Hi,
> 
> I'm new to MASON and tried creating a very simple simulation following the manual's student example but changing it to a sparse grid (2D).  It compiles fine, but when I try to run it I can't see any agents.  My student also created her own simulation and has the same problem.  The main similarity between us is that we are running java 1.6 on Mac OSX with Eclipse. Her code is not the same as mine which is what is leading me to believe we either both missed something obvious or one of these 3 factors is why the visualization is failing...
> 
> Any ideas on what could be causing this issue?  I'm copying my classes below in case that helps.
> 
> Thanks!
> Megan
> 
> package sim.app.simplepredprey;
> 
> import sim.portrayal.grid.*;
> import sim.engine.*;
> import sim.display.*;
> import sim.portrayal.simple.*;
> import javax.swing.*;
> import java.awt.Color;
> 
> /**
>  * Creates all of the GUI elements, including console and visualization
>  * Grid is 2D, and elements to display are circles
>  * @author megan olsen
>  *
>  */
> public class SimulationWithUI extends GUIState{
> 
> public Display2D display;
> public JFrame displayFrame;
> SparseGridPortrayal2D gridPortrayal = new SparseGridPortrayal2D();
> private final short worldwidth = 100; //update when update in Simulation
> private final short worldheight = 100; //update when update in Simulation
> /**
> * directly from tutorial in manual.pdf
> */
> public static void main(String[] args)
> {
> SimulationWithUI vid = new SimulationWithUI();
> Console c = new Console(vid);
> c.setVisible(true);
> }
> /**
> * directly from tutorial in manual.pdf
> */
> public SimulationWithUI() { super(new Simulation(System.currentTimeMillis())); }
> public SimulationWithUI(SimState state) { super(state); }
> public static String getName() { return "Predator Prey Simulation"; }
> /**
> * directly from tutorial in manual.pdf
> */
> public void start()
> {
> super.start();
> setupPortrayals();
> }
> /**
> * directly from tutorial in manual.pdf
> */
> public void load(SimState state)
> {
> super.load(state);
> setupPortrayals();
> }
> /**
> * directly from tutorial in manual.pdf with minor adjustments
> */
> public void setupPortrayals()
> {
> Simulation sims = (Simulation) state;
> //tell the portrayals what to portray and how to portray them
> gridPortrayal.setField(sims.grid);
> OvalPortrayal2D oval = new OvalPortrayal2D(Color.black);
> gridPortrayal.setPortrayalForAll(oval);
> //reschedule the displayer
> display.reset();
> //redraw the display
> display.repaint();
> }
> /**
> * directly from tutorial in manual.pdf with minor adjustments
> */
> public void init(Controller c)
> {
> super.init(c);
> display = new Display2D(worldwidth,worldheight,this);
> display.setClipping(false);
> displayFrame = display.createFrame();
> displayFrame.setTitle("Predator Prey Display");
> c.registerFrame(displayFrame); //so the frame appears in the display list
> displayFrame.setVisible(true);
> display.setBackdrop(Color.green);
> display.attach(gridPortrayal, "Grid");
> }
> /**
> * directly from tutorial in manual.pdf
> */
> public void quit()
> {
> super.quit();
> if(displayFrame!=null)
> displayFrame.dispose();
> displayFrame = null;
> display = null;
> }
> }
> 
> package sim.app.simplepredprey;
> 
> import sim.engine.*;
> import sim.util.*;
> import sim.field.grid.*;
> 
> /**
>  * Main Model class. Holds the world grid and all agents.  Controls time steps.
>  * @author megan olsen
>  *
>  */
> public class Simulation extends SimState{
> 
> /**
> * The world - type allows multiple objects at each integer location
> */
> public SparseGrid2D grid;
>    
> /**
> * width of the world
> */
> private final int gridWidth;
> /**
> * height of the world
> */
> private final int gridHeight;
> /**
> * the number of predator agents in the start of the simulation
> */
> private short numPred;
> //private short numPrey;
> public Simulation(long seed)
> {
> super(seed);
> gridWidth = 100;
> gridHeight = 100;
> numPred = 2;
> //
> numPrey = 10;
> }
> /**
> * For setup of the model. Clears the grid and creates the initial agents,
> * setting the agents to be scheduled at each time step.
> * @author megan olsen
> * @param none
> * @return none
> */
> public void start()
> {
> super.start();
> grid = new SparseGrid2D(gridWidth, gridHeight);
> //grid.clear();
> /*
> for(int i=0; i<numPred; i++)
> {
> Predator p = new Predator();
> grid.setObjectLocation(p,  new Int2D(grid.getWidth()/2+random.nextInt(grid.getWidth()/2), 
> grid.getHeight()/2 - random.nextInt(grid.getHeight()/2)));
> schedule.scheduleRepeating(p);
> }*/
> Predator p = new Predator();
> grid.setObjectLocation(p, new Int2D(50,50));
> schedule.scheduleRepeating(p);
> /* for(int j=0; j<numPrey; j++)
> {
> }*/
> }
> /**
> * Runs the simulation using the built in "doLoop" that steps through scheduled agents.
> * @param args
> */
> public static void main(String[] args)
> {
> doLoop(Simulation.class, args);
> System.exit(0);
> }
> }
> 
> package sim.app.simplepredprey;
> 
> import sim.engine.*;
> import sim.field.grid.*;
> import sim.util.*;
> 
> /**
>  * Simple agent class for predators
>  * @author megan olsen
>  *
>  */
> public class Predator implements Steppable{
> 
> //location is built in -- ObjectLocation
> /**
> * The method controlling what each agent does at each time step.
> * @author megan olsen
> * @param state the SimState object, used to interact with the world and other agents
> */
> public void step(SimState state)
> {
> //get access to the world through the parameter
> Simulation mysim = (Simulation) state;
> SparseGrid2D grid = mysim.grid;
> Int2D location = grid.getObjectLocation(this); //this agent's location
> //Int2D can't be changed, so we must create a mutable int to set a new location
> /*
> MutableInt2D newloc = new MutableInt2D();
> newloc.x = grid.tx(location.x + 1);
> newloc.y = grid.ty(location.y + 1);
> System.out.println(newloc.x + " " + newloc.y);
> grid.setObjectLocation(this, new Int2D(newloc));*/
> }
> }